Title:
Behavior of Gravity Load Design Reinforced Concrete Buildings Subjected to Earthquakes
Author(s):
Adel G. El-Attar, Richard N. White, and Peter Gergely
Publication:
Structural Journal
Volume:
94
Issue:
2
Appears on pages(s):
133-145
Keywords:
earthquake-resistant structures; frames; joints (junctions);
office buildings; reinforced concrete;
DOI:
10.14359/468
Date:
3/1/1997
Abstract:
Two smallscale reinforced concrete building models were tested on the Cornell University shake table. The models were a 1/6 scale twostory office building and a 1/8 scale threestory onebay by threebays office building. Both structures were designed to resist purely gravity loads without regard to lateral loads (wind or earthquake forces). The reinforcement details were based on typical reinforced concrete frame structures constructed in the central and eastern United States over the past 50 to 60 years, as characterized by (a) low reinforcement ratio in the columns, (b) discontinuous positive moment reinforcement in the beams at the column locations, (c) little or no confining reinforcement in the joint regions, and (d) lap splices located immediately above the floor level. Both models were tested using the timecompressed Taft 1952 S69E ground motion scaled to increasingly large peak ground accelerations. Test results indicated that gravity load design (GLD) reinforced concrete buildings without walls will experience very large deformations associated with a considerable stiffness degradation during a moderate earthquake. The high flexibility produced significant PD effects in the threestory building model. Although the nonseismic details associated with the gravity load design philosophy forms a source of damage, the experiments indicate that these details will not necessarily lead to collapse or a complete failure mechanism. Comparison with analytical results indicated that inclusion of the slab contribution to beam flexural strength is a vital step in the assessment of the performance of GLD reinforced concrete structures since it has the potential of altering the relatively ductile strong columnweak beam mechanism to a more brittle softstory mechanism.